GETCWD(3)                                           Linux Programmer's Manual                                          GETCWD(3)



NAME
       getcwd, getwd, get_current_dir_name - Get current working directory

SYNOPSIS
       #include <unistd.h>

       char *getcwd(char *buf, size_t size);

       char *getwd(char *buf);

       char *get_current_dir_name(void);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getcwd(): _BSD_SOURCE || _XOPEN_SOURCE >= 500
       get_current_dir_name(): _GNU_SOURCE

DESCRIPTION
       These  functions return a null-terminated string containing an absolute pathname that is the current working directory of
       the calling process.  The pathname is returned as the function result and via the argument buf, if present.

       The getcwd() function copies an absolute pathname of the current working directory to the array pointed to by buf,  which
       is of length size.

       If  the  length  of  the absolute pathname of the current working directory, including the terminating null byte, exceeds
       size bytes, NULL is returned, and errno is set to ERANGE; an application should check for  this  error,  and  allocate  a
       larger buffer if necessary.

       As an extension to the POSIX.1-2001 standard, Linux (libc4, libc5, glibc) getcwd() allocates the buffer dynamically using
       malloc(3) if buf is NULL.  In this case, the allocated buffer has the length size unless size is zero, when buf is  allo-
       cated as big as necessary.  The caller should free(3) the returned buffer.

       get_current_dir_name() will malloc(3) an array big enough to hold the absolute pathname of the current working directory.
       If the environment variable PWD is set, and its value is correct, then that value will be returned.   The  caller  should
       free(3) the returned buffer.

       getwd()  does  not  malloc(3) any memory.  The buf argument should be a pointer to an array at least PATH_MAX bytes long.
       If the length of the absolute pathname of the current working directory, including the  terminating  null  byte,  exceeds
       PATH_MAX  bytes,  NULL  is returned, and errno is set to ENAMETOOLONG.  (Note that on some systems, PATH_MAX may not be a
       compile-time constant; furthermore, its value may depend on the file system, see pathconf(3).)  For portability and secu-
       rity reasons, use of getwd() is deprecated.

RETURN VALUE
       On  success,  these  functions return a pointer to a string containing the pathname of the current working directory.  In
       the case getcwd() and getwd() this is the same value as buf.

       On failure, these functions return NULL, and errno is set to indicate the error.  The contents of the array pointed to by
       buf are undefined on error.

ERRORS
       EACCES Permission to read or search a component of the filename was denied.

       EFAULT buf points to a bad address.

       EINVAL The size argument is zero and buf is not a null pointer.

       EINVAL getwd(): buf is NULL.

       ENAMETOOLONG
              getwd(): The size of the null-terminated absolute pathname string exceeds PATH_MAX bytes.

       ENOENT The current working directory has been unlinked.

       ERANGE The  size argument is less than the length of the absolute pathname of the working directory, including the termi-
              nating null byte.  You need to allocate a bigger array and try again.

CONFORMING TO
       getcwd() conforms to POSIX.1-2001.  Note however that POSIX.1-2001 leaves the behavior of getcwd() unspecified if buf  is
       NULL.

       getwd()  is present in POSIX.1-2001, but marked LEGACY.  POSIX.1-2008 removes the specification of getwd().  Use getcwd()
       instead.  POSIX.1-2001 does not define any errors for getwd().

       get_current_dir_name() is a GNU extension.

NOTES
       Under Linux, the function getcwd() is a system call (since 2.1.92).  On older systems it would query /proc/self/cwd.   If
       both system call and proc file system are missing, a generic implementation is called.  Only in that case can these calls
       fail under Linux with EACCES.

       These functions are often used to save the location of the current working directory for the purpose of returning  to  it
       later.   Opening the current directory (".") and calling fchdir(2) to return is usually a faster and more reliable alter-
       native when sufficiently many file descriptors are available, especially on platforms other than Linux.

SEE ALSO
       chdir(2), fchdir(2), open(2), unlink(2), free(3), malloc(3)

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                                                        2009-03-31                                                  GETCWD(3)